Lock jsk->sk to prevent UAF when setsockopt(..., SO_J1939_FILTER, ...) modifies jsk->filters while receiving packets.

Following trace was seen on affected system: ================================================================== BUG: KASAN: slab-use-after-free in j1939_sk_recv_match_one+0x1af/0x2d0 [can_j1939] Read of size 4 at addr ffff888012144014 by task j1939/350

CPU: 0 PID: 350 Comm: j1939 Tainted: G W OE 6.5.0-rc5 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: print_report+0xd3/0x620 ? kasan_complete_mode_report_info+0x7d/0x200 ? j1939_sk_recv_match_one+0x1af/0x2d0 [can_j1939] kasan_report+0xc2/0x100 ? j1939_sk_recv_match_one+0x1af/0x2d0 [can_j1939] __asan_load4+0x84/0xb0 j1939_sk_recv_match_one+0x1af/0x2d0 [can_j1939] j1939_sk_recv+0x20b/0x320 [can_j1939] ? __kasan_check_write+0x18/0x20 ? __pfx_j1939_sk_recv+0x10/0x10 [can_j1939] ? j1939_simple_recv+0x69/0x280 [can_j1939] ? j1939_ac_recv+0x5e/0x310 [can_j1939] j1939_can_recv+0x43f/0x580 [can_j1939] ? __pfx_j1939_can_recv+0x10/0x10 [can_j1939] ? raw_rcv+0x42/0x3c0 [can_raw] ? __pfx_j1939_can_recv+0x10/0x10 [can_j1939] can_rcv_filter+0x11f/0x350 [can] can_receive+0x12f/0x190 [can] ? __pfx_can_rcv+0x10/0x10 [can] can_rcv+0xdd/0x130 [can] ? __pfx_can_rcv+0x10/0x10 [can] __netif_receive_skb_one_core+0x13d/0x150 ? __pfx___netif_receive_skb_one_core+0x10/0x10 ? __kasan_check_write+0x18/0x20 ? _raw_spin_lock_irq+0x8c/0xe0 __netif_receive_skb+0x23/0xb0 process_backlog+0x107/0x260 __napi_poll+0x69/0x310 net_rx_action+0x2a1/0x580 ? __pfx_net_rx_action+0x10/0x10 ? __pfx__raw_spin_lock+0x10/0x10 ? handle_irq_event+0x7d/0xa0 __do_softirq+0xf3/0x3f8 do_softirq+0x53/0x80 </IRQ> <TASK> __local_bh_enable_ip+0x6e/0x70 netif_rx+0x16b/0x180 can_send+0x32b/0x520 [can] ? __pfx_can_send+0x10/0x10 [can] ? __check_object_size+0x299/0x410 raw_sendmsg+0x572/0x6d0 [can_raw] ? __pfx_raw_sendmsg+0x10/0x10 [can_raw] ? apparmor_socket_sendmsg+0x2f/0x40 ? __pfx_raw_sendmsg+0x10/0x10 [can_raw] sock_sendmsg+0xef/0x100 sock_write_iter+0x162/0x220 ? __pfx_sock_write_iter+0x10/0x10 ? __rtnl_unlock+0x47/0x80 ? security_file_permission+0x54/0x320 vfs_write+0x6ba/0x750 ? __pfx_vfs_write+0x10/0x10 ? __fget_light+0x1ca/0x1f0 ? __rcu_read_unlock+0x5b/0x280 ksys_write+0x143/0x170 ? __pfx_ksys_write+0x10/0x10 ? __kasan_check_read+0x15/0x20 ? fpregs_assert_state_consistent+0x62/0x70 __x64_sys_write+0x47/0x60 do_syscall_64+0x60/0x90 ? do_syscall_64+0x6d/0x90 ? irqentry_exit+0x3f/0x50 ? exc_page_fault+0x79/0xf0 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

Allocated by task 348: kasan_save_stack+0x2a/0x50 kasan_set_track+0x29/0x40 kasan_save_alloc_info+0x1f/0x30 __kasan_kmalloc+0xb5/0xc0 __kmalloc_node_track_caller+0x67/0x160 j1939_sk_setsockopt+0x284/0x450 [can_j1939] __sys_setsockopt+0x15c/0x2f0 __x64_sys_setsockopt+0x6b/0x80 do_syscall_64+0x60/0x90 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

Freed by task 349: kasan_save_stack+0x2a/0x50 kasan_set_track+0x29/0x40 kasan_save_free_info+0x2f/0x50 __kasan_slab_free+0x12e/0x1c0 __kmem_cache_free+0x1b9/0x380 kfree+0x7a/0x120 j1939_sk_setsockopt+0x3b2/0x450 [can_j1939] __sys_setsockopt+0x15c/0x2f0 __x64_sys_setsockopt+0x6b/0x80 do_syscall_64+0x60/0x90 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

Fixes: 9d71dd0c70099 ("can: add support of SAE J1939 protocol") Reported-by: Sili Luo rootlab@huawei.com Suggested-by: Sili Luo rootlab@huawei.com Acked-by: Oleksij Rempel o.rempel@pengutronix.de Cc: stable@vger.kernel.org Signed-off-by: Oleksij Rempel o.rempel@pengutronix.de --- changes v2: - spin_lock_bh() instead of lock_sock()

net/can/j1939/j1939-priv.h | 1 + net/can/j1939/socket.c | 22 ++++++++++++++++++---- 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/net/can/j1939/j1939-priv.h b/net/can/j1939/j1939-priv.h index 16af1a7f80f6..c4d098362155 100644 --- a/net/can/j1939/j1939-priv.h +++ b/net/can/j1939/j1939-priv.h @@ -301,6 +301,7 @@ struct j1939_sock {

int ifindex; struct j1939_addr addr; + spinlock_t filters_lock; struct j1939_filter *filters; int nfilters; pgn_t pgn_rx_filter; diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c index 14c431663233..641d37671c19 100644 --- a/net/can/j1939/socket.c +++ b/net/can/j1939/socket.c @@ -262,12 +262,17 @@ static bool j1939_sk_match_dst(struct j1939_sock *jsk, static bool j1939_sk_match_filter(struct j1939_sock *jsk, const struct j1939_sk_buff_cb *skcb) { - const struct j1939_filter *f = jsk->filters; - int nfilter = jsk->nfilters; + const struct j1939_filter *f; + int nfilter; + + spin_lock_bh(&jsk->filters_lock); + + f = jsk->filters; + nfilter = jsk->nfilters;

if (!nfilter) /* receive all when no filters are assigned */ - return true; + goto filter_match_found;

for (; nfilter; ++f, --nfilter) { if ((skcb->addr.pgn & f->pgn_mask) != f->pgn) @@ -276,9 +281,15 @@ static bool j1939_sk_match_filter(struct j1939_sock *jsk, continue; if ((skcb->addr.src_name & f->name_mask) != f->name) continue; - return true; + goto filter_match_found; } + + spin_unlock_bh(&jsk->filters_lock); return false; + +filter_match_found: + spin_unlock_bh(&jsk->filters_lock); + return true; }

static bool j1939_sk_recv_match_one(struct j1939_sock *jsk, @@ -401,6 +412,7 @@ static int j1939_sk_init(struct sock *sk) atomic_set(&jsk->skb_pending, 0); spin_lock_init(&jsk->sk_session_queue_lock); INIT_LIST_HEAD(&jsk->sk_session_queue); + spin_lock_init(&jsk->filters_lock);

/* j1939_sk_sock_destruct() depends on SOCK_RCU_FREE flag */ sock_set_flag(sk, SOCK_RCU_FREE); @@ -703,9 +715,11 @@ static int j1939_sk_setsockopt(struct socket *sock, int level, int optname, }

lock_sock(&jsk->sk); + spin_lock_bh(&jsk->filters_lock); ofilters = jsk->filters; jsk->filters = filters; jsk->nfilters = count; + spin_unlock_bh(&jsk->filters_lock); release_sock(&jsk->sk); kfree(ofilters); return 0;